How do I make a landscape like this? (Sea, waves, shore, beach...)
You could create 2 objects, one for the ground:

Select some random vertices and move them up:

Extrude the whole plane down:

Create the sea:

Give it a Subdivision Surface modifier. Give it a Displace modifier with a texture Cloud in order to have a bit of noise, with Coordinates &gt; Object and an empty as Object that you will move and keyframe. At last, give it a Wave modifier with this kind of settings:

Now give a texture to the ground that is basically a gradient on the Z axis:

Give a texture to the water that is a mix between Glass, Transparent and Glossy:

Give your whole scene an HDRI:

If you're supposed to make a part of your water flater (or decrease the modifiers effect), switch your sea object to Weight Paint mode, paint this part:

Then in the modifiers, select the group you've just selected, switch with the &lt;-&gt; button: